My first post

Firstly I'd like to thank all the experts here who are willing to help the DYSers. I am in a different trade, more commercial, but I also like to help other people do things the right way if I can. Thanks again. I am building a new home myself from the ground up. Currently just in the planning stages, I will be putting in two main floor bathrooms with almost back to back water closets common to the water wall. There will be about 4 feet between the centers of the toilet flanges. I want to place the stack in the best location and I have my first of many questions ( I'll post more questions later ) The question is can I enter the vertical 3 inch pipe with what would be like a double "Y" fitting or should I put one entry just below the other. The stack will be straight up vented and the area underneath the floor joists is a 4 foot crawl space. After the toilets are connect the 3 or what could be 4 inch drain pipe will travel in a sloped / horizontal run about 30 feet to exit the crawlspace into the main drain. Hope this question makes sense. I am in Canada. Thanks to all who reply.

neither a ]"double Y", nor a sanitary cross, is the correct fitting. You want a "back to back fixture fitting", which halfway between a sanitary cross and a double combination Y-1/8 bend. For two toilets, all you need is a 3" drain line. There are many good locations for the vertical line between the toilets, the BEST one will depend on HOW the toilets line up with the floor framing.

Thanks for your reply, the good thing here is the floor joists are not framed yet, easy to reposition the joists or do a "hatch frame" as required to get a well planned out drain system. I went to the canplas website but could not find the fitting you speak of, can you post a picture ?? The entire system will consist of 2 tubs, almost back to back and 2 sinks back to back. I will post a picture as soon as I figure out how Thanks again.

canplas does make a double fixture fitting (abs), but you will have to look hard for the #. Don't expect the guys at the counter to know what you are talking about, and certainly not the big box helper. It will also cost you around 50 bux or so for the one fitting.

Under the floor is just a crawlspace, never to developed. For me this is just about doing it correctly, it will be inspected, and having it work well. I've attached pictures for you experts to pick apart , please do.

I have lots of room and don't mind buying extra pipe . With all the fancy toilets out there I don't want any "flushing" problems after the house is built. That being said, is this revised arrangement better ?? Thanks BTW the trap arms should read 1 1/2 not 1/2 as shown.

So now I am curious, when would you / can you use the double fixture T. In my case I can see the drain possibly going in the wrong direction or as mentioned in a previous post it could an issue during snaking or other maintenance.

Yes, I am curious as to why a double fixture tee cannot be used for the sinks either. And yes, a double fixture tee really is that expensive here in Canada. Maybe in the States they seem to stock it at the big box stores, but here it is a special order item, so by the time you factor in shipping from the factory, it does cost 50 bux.

In the United States, it has to be a fixture cross like the one pictured in hj's post.
You can use a double tee as a vent fitting, not for waste.
I realize that Canada is different, so maybe it doesn't matter if it can't be snaked.
We also use 2" where the two meet, not 1.5"

But not in the USA. Canada uses a double tee, the United States uses a double fixture fitting. Since this guy is in Canada, it doesn't really matter. He could use a rubber hose into a bucket and it would pass inspection.

Double fixture fitting for two lavs, for plumbing in 50 States, but not needed in Canada.

So now I am curious, when would you / can you use the double fixture T. In my case I can see the drain possibly going in the wrong direction or as mentioned in a previous post it could an issue during snaking or other maintenance.

Click to expand...

I don't know what Canada code says but in the U.S. if you are using the UPC (Uniform Plumbing Code) you can use a double fixture fitting (No. 5 fitting) at all three of your sections on your drawing, including the toilets.

Yes, the Canadian code is behind the time and allows for the use of a double santee to connect back to back fixtures, but any decent plumber knows not to use that fitting there. The original poster knows he has to use a double fixture tee (what you are calling a double fixture fitting) as is described in his drawings. A regular cross is referred to as a double santee here.

While I do agree that the UPC is an excellent code overall, it is also a very expensive and sometimes inefficient way to plumb in my opinion. And I don't even think half the states in your country use that code.

Well, I am 45 min. from the US border so maybe I'll look for them the next time I am over at least for the two sinks, otherwise here it is in the Canadian Plumbing Code book.......... On another thought; because I have plenty of room in the crawl space do you all think I should split up and separate vent each arm of the tub drains to be sure of no future problems ?? ( now is the time to spend an extra 30 bucks on pipe and fittings)

Attached Files:

I am also guessing there is no exact requirement as to the height in the wall of the trap arm connection as long as it meets the rules of common sense ??? ( Terry, I like that rubber hose idea ). Here is my latest attempt at meeting the Canadian Code but really appreciate all the advice both Canadian & US. Your opinions please on this latest drawing.